Method of purifying non-oxidizing organic anhydrids.



me ts UNITED sTArEsraIENT; OFFIQE,

enons onnsTEI'N, or NIAGARA rams, NEW YORK, ns srenon ro' Hooimn Emerge,

' summon COMPANY, ornnw YORK, N. Y., A oonroa'arxolvor, NEW roam,

METHOD or rumrrrirenoN-oxmmme m m um-sa No Drawing.

To all whom it may-wacemz- Be it known that 1, Gross ORNsTEiN, a subject of the Emperor of Germany, residing at Niagara Falls, in the county OfNlagara and State of New York, have'invented certain new and useful Improvements in Methods of Purifying Non-Oxi'dizingOr- .upon acetates of sodium, calcium or the like,

ormixtures of these, with such reagents as sul'furyl chlorid, chlorid of sulfur,'or mixtures of sulfur dioxid and chlorin, is usually contaminated by sulfur chlorid and other impurities, the proportion of which may vary somewhat according to the conditions of preparation, the vimpurities bein however always present to an objectiona le degree. Even when an excess of the acetate is present in the reacting mixture the distillate is found to contain small proportions of dichlorid of sulfur, the presence of which in the technical product is highly objectionable. Owing to the fact that the boiling points of acetic anhydrid and sulfur dichlorid are substantially identical, re-distillation or fractionatin is quite ineffectual for the further purification of the product.

I have discovered that the acetic anhydrid prepared as above may be quickly and effectively purified to a degree sufficient for most technical purposes by treatment with suitable oxidizing agents, whereby the sulfur compounds are oxidized without loss of anhydrid. The oxidation of the sulfur gives rise to some sulfuric acid in the product, but

this is not an objectionable impurity for such Specification of Letters Patent.

Application fledtoctob'r 14, 1910.- Serial no. 587,037. a

f math 5,1191% sulfuric 'afcidasia step p l ar I manufacture of cellulose acetates either more, in c ase' it is'desiredtoprepare a prod;

not, free from sulfuric "acid; this: is;. irmst eas ly accomplished 'by ia second "distillation. Example: Tcth'e cruae dark coloredYaceti'c anhydrid prepared, for instance, by reacting with sulfur dichlorid upon sodimn-acetate and distilling the product, there is added from -one-fourth to one per cent. by weight portion of sulfur present, T e liquid is then heated to the boiling point under a refiux condenser, and continues to boil for to the of fuming nitric acid, accordin to the proof the anhydrid in ammonia and adding silver nitrate, whereby thesilver is precl itated as sulfid. The oxidation of the sul r by the ozone is less complete than with nitric acid, and the decolorization of the liquid is somewhat less pronounced.

Other oxidizing agents, as chromic acid, potassium permanganate, etc., are effective as regards the elimination ofsulfur chlorid, butin'most cases asecond distillation is required to obtain a-c olorless or light colored product. The particular advantage of nitric acid, preferably employed as the fum- I ing acid, is that it is not only very effective in oxidizing the sulfur, but also ields directly and without further distlllation a product which fulfils in all respects the technical requirements as 'tocolor and purity.

I claim:

1. The method of treating'such organic anhydrids as are themselves-resistant to oxidation but contain oxidizable impurities, which comprises acting thereon with a suitable oxidizing agent under conditions to oxidize the impurities contained therein.

2. The method of treating such organic anhydrids as are themselves resistant to oxidation but contain. oxidizable impurities, which comprises acting thereon with fuming nitric acid under Conditions to oxidize the impurities contained therein.

3. The method of treating such organic anhydrids asare themselves resistant to oxidation but contain oxidizable impurities, which comprises acting thereon with a suitable oxidizing agent under conditions to oxidize the impurities contained therein, and distilling the product.

4. The method of treating acetic anhydrid containing oxidizable impurities, which comprises acting thereon with a suitable oxidizing agent under conditions to oxidize the impurities contained therein.

5. The method of treating acetic anhydrid containing oxidizable impurities, which j containing comprises acting thereon with fuming nitric acid under conditions tooxidize the impurities contained therein. 6. The method of treating acetic anhydrid oxidizable impurities, which comprises acting thereon with a suitable oxidizing agent under conditions to oxidize the impurities contained therein, and distilling the product.

In testimony whereof, I afiix my signature in presence of two witnesses;

GEORG ORNSTEIN.

Witnesses: A

Enw. E. Fmucnor, FREDERICK CHORMANN. 

